Changing break master cylinder?

ok so i took in my car to a dealer and ive been told that i need to change my master cylinder because it had some contaminant in it that was a lubricant which ruined my rubber seals and stuff in the master cylinder. The price they gave me was from 2000-3000$ to get it fully repaired. I looked up the price of the master cylinders and they lye between 100-200$... so it would save me alot if i just do it myself.. or is there more to it?? How hard will it be to do it myself?